After all singles automatically I directly looked at columns 12.. This is another "extreme" example of distinctions.. 2 is locked in r23c2, so we can see c12 as distinction 1. Thus r23c2(6) can be eliminated, also no pair outside these columns can be switched, specifically r78c5. If they are 36 then swap them and adjust c12 we can always get another solution(impossible).So r7c5=8.

For those not familiar with it, maybe this point of view helps:r7c12 cannot be 36, otherwise you would have a reversed bug lite, or, if you like, an 8 cell unique loop with 14 in r8c12.

To the hidden grid:

... also no pair outside these columns can be switched ...

You have to be careful. This is only true for the undecided rows in c12, here 16789, not e.g. r23c6 and c9. The pair 69 in c6 can be true for a unique solution, and a pair must be true in c9.

Additionally you could use, that rows 12 cannot have distinction 1 too, i.e. it is not possible, that - if r2c2 is not 2 - r2c3=1 and r2c79=2. So one of 12 has to be in r2c2, 469 could be eliminated there.

btw there is a typo: should be r8c6(23) in the non-uniqueness solution.